Conventionally, a probe head is assembled on a probe card for probing the semiconductor wafer under test. The conventional probe card comprises a probe head and a multi-layer printed circuit board shaped like a disk. Because the contact elements of probe head, such as probe needles or probing bumps, are required to contact the bonding pads of a wafer precisely, the precision and the matching of coefficient of thermal expansion of a probe head is higher than that of other probe card components. Therefore, the probe head is a key component of a probe card.
A probe card with a probe head containing an interconnect substrate with raised contact members is disclosed in U.S. Pat. No. 6,359,456. The interconnect substrate is made of silicon by semiconductor fabricating process. Conductive circuits and raised contact members are formed on the active surface of interconnect substrate as a probe head. There is no electric connection formed on the corresponding back surface of interconnect substrate, the conductive circuits of interconnect substrate are formed on the active surface with contact members and extend to edges of the active surface. The conductive circuits of interconnect substrate are connected by bonding wires to a mounting plate, and then use a membrane to connect the mounting plate to testing apparatus. The bonding wires and the membrane provide a hoop height higher than the active surface of the silicon interconnect substrate. While the raised contact members on the active surface of interconnect substrate probing the electrodes of a wafer under test, however, these bonding wire or flexible membrane are possibly to contact and rub against the wafer under test, which may damage the wafer under test and also affecting the testing results.